1. Field of the Invention
The present invention relates to a three-dimensional filter, a two-dimensional filter and a video filter apparatus capable of suppressing noises and distortions by correcting a luminance signal of a video decoder of, for example, MPEG.
2. Description of the Related Art
FIG. 8 is a block diagram showing conventional circuits of processing output signals from a MPEG video decoder 12. In FIG. 8, like elements to those of an embodiment of the invention are represented by using identical reference numerals and the detailed description thereof is omitted by explaining only the main points thereof. The MPEG video decoder 12 decodes MPEG video data and separately outputs a luminance signal Yu and color difference signals Cb and Cr. The luminance signal Yu is supplied to a one-dimensional interpolation filter 70 and the color difference signals Cb and Cr are supplied to a delay adjustment delay line 72 to be processed thereat and supplied to a television monitor (not shown) via a video DAC.
The problems associated with conventional video filter apparatuses are enumerated in the following.
(a) Generation of distortions if an encoder uses a high compression factor (e.g., a lot bit rate at about 3 Mbps), the distortions including:
horizontal and vertical direction block distortions in two-dimensional DCT, and mosquito noises; and
flickers by motion compensation (using interframe difference).
(b) Generation of distortions caused by deteriorated input image sources themselves, the distortions including:
low S/N; PA1 flickers, and PA1 random noises.